The present invention generally relates to a vehicular lamp having an improved lens structure mounted over the front opening of a lamp housing. More specifically, the present invention is directed to a light diffusion reflecting structure provided at a flange portion of the lens adjacent an inner wall of the opening of a lamp chamber formed within the lamp housing.
Conventionally, a reflection-type arrangement is employed in lamps for automotive use including a so-called combination lamp in which a back-up lamp and a tail and stop lamp are arranged parallel to one another.
As shown in FIG. 6, in a typical reflection-type lamp, light sources 53 (bulbs) are arranged within lamp chambers 51, positioned in front of reflectors 52 provided at the rear portions of the respective lamp chambers 51. The lamp chambers 51 are separated and segmented by a segment wall 50.
In a combination lamp of the reflection type, front lenses or outer lenses 55 cover the opening of a lamp housing 54. Further, inner lenses 56 are provided for achieving certain lighting effects such as a desired color and light distribution, depending upon whether the particular lamp is to be used as a tail and stop lamp, back-up lamp, etc. The inner lenses 56 are arranged parallel to the outer lenses 55 to the rear thereof. In this arrangement, light radiated from the light source 53 is reflected by the reflector 52 and also transmitted through an inner lens 56, thereby to obtain an output light distribution in accordance with the intended purpose of the lamp.
In such a conventional combination-type lamp, a fixing groove 59 is provided integrally at the peripheral portion of the lamp housing 54, and a seal leg portion 57 for the front lens or the outer lens 55 is fitted into the groove and fixed therein by an adhesive 58 or the like. The inner lens 56 is positioned inside the front lens or the outer lens, arranged parallel thereto. The flange portion 60 formed on the peripheral portion of the inner lens 56 so as to extend rearward is adhered along the inner wall of the opening portion of the lamp housing 54. Otherwise, the flange portion 60 may be disposed so as to be movable in the front and rear direction by a guide structure (not shown).
In the thus-constructed conventional lamp, some of the light L2 emitted by the light source 53 is reflected by the flange portion 60 at the peripheral portion of the inner lens 56. Also, some of the light L2 emitted by the light source 53 is transmitted through the flange portion 60 and reflected by the inner surface of the lamp housing 54. The reflected light beam is projected through the front lens or the outer lens 55. As a result, the flange portion is brightened so as to appear lighter than other portions because the reflected light beam is superimposed on the light beam L1 reflected from the reflector 52. Accordingly, the conventional lamp has a problem that the output light beam emitted through the front lens or the outer lens 55 of the lamp is not uniform, thereby causing the lamp to have a generally poor outer appearance when lit.